package com.mingdong.first.waiguan.hometheater;

public class Screen {

	private static Screen instance = null;
			
	private Screen(){
		
	}
	
	public static Screen getInstance(){
		
		if(instance == null){
			instance = new Screen();
		}
		return instance;
	}
	
	public void up(){
		System.out.println("Screen up");
	}
	
	public void down(){
		System.out.println("Screen down");
	}	
}
